Wireless networks may use an automatic repeat request protocol to control errors in transmission. For example, the Long Term Evolution (LTE) network may use the Hybrid Adaptive Repeat Request (HARQ) protocol, in the uplink and/or the downlink.
The LTE downlink HARQ mechanism uses an asynchronous HARQ protocol. Retransmissions in the LTE downlink HARQ mechanism may occur in the downlink cell bandwidth. Retransmissions may often be on the same HARQ as the initial transmission after the initial unsuccessful transmission. Retransmissions may be scheduled on a particular HARQ similar to the initial transmission.
The LTE uplink HARQ mechanism may include a synchronous HARQ protocol. In this protocol, the time instance of a retransmission may be fixed with respect to the initial transmission.